There are two types of roof-mounted known structures for collecting solar energy, one, in which a heating medium sealed in a transparent sheet is heated by means of solar energy to make use of the resultant heat; and another, in which a solar energy collection roof member made of amorphous silicon or crystalline silicon is mounted on the back side of a light transmitting sheet.
However, when the entire surface of a roof is covered with solar energy collection members, the cost goes up and a large number of solar energy collection roof members of different dimensions are required used in combination with each other to correspond to the size of the roof surface. Also, the roof increases the weight, so that rafters and sheathing boards have to bear substantial weight. Since each of these conventional structures is complicated in structure and includes a large number of members, the erection of such conventional roof mounted roof structures is troublesome, and the correction of dimensional errors is troublesome, so that it has been impossible to provide a roof with a sufficient surface for use in collecting of solar energy.